1. Field of the Invention
The present invention relates to a deep dyeing process of a polyamide (PA or nylon including Nylon 4, Nylon 6, Nylon 46, Nylon 66, Nylon 7, Nylon 8, Nylon 9, Nylon 610, Nylon 1010, Nylon 11, Nylon 12, Nylon 13, Nylon 612, Nylon 9T, Nylon 13, MC Nylon, Nylon MXD6 and all polyamide derivatives) and a polyolefin (including ethylene copolymer, propylene copolymer, and related derivatives), and the deep dyeing process uses a compatibilizer precursor and an amino, hydroxyl or epoxy group containing chemical to modify the polyamide and polyolefin, and the modified polyamide and polyolefin has a low-temperature dyeability, and finally uses a reactive dye and/or an acid dye to perform the dyeing process, such that the dyed polyamide and polyolefin fibers have excellent dye fastness, light fastness, rubbing fastness and washing fastness.
2. Description of Related Art
In general, polyamide (PA) or nylon is a linear condensation polymer composed of repeated primary bonds of amide groups (—CONH—), and featuring high crystallization, chemical resistance, oil resistance, solvent resistance, and abrasion resistance, a small coefficient of friction, a high level of thermal degradation, a broad manufacturing scope, and a self-lubrication. In addition, the mechanical properties of nylon has the advantages of high tensile strength, high impact resistance and excellent elasticity, tenacity and extensibility, and thus nylon can be used extensively as a composite material for the textile industry, an industrial fiber or an agent for enhancing fibers.
The structure of nylon is characterized in that an end of its molecular chain includes a functional group such as a carboxyl group (—COOH) and an amino group (—NH2) having a good dyeability, and a large number of carbon-hydrogen bonds (—CH2) and amide groups (—NHCO—) at the middle of the molecular chain, and thus various different types of dyes such as ionic dyes, acid mordant dyes, metal complex acid dyes, direct dyes, dispersive dyes, azo dyes, vat dyes, and acid dyes can be used for dyeing nylon fibers, and the dyeability of fibers depends on the dispersion of the dye and the affinity between the fibers and dye as well as their connection. In the aforementioned dyes, only the acid dye contains hydrophilic groups of sodium sulfonate radicals (—SO3Na) that can be combined with the amino groups (—NH+) of the nylon fibers by the ionic bonds or electrostatic forces to provide better dyeability and brighter color, and the rest of the aforementioned dyes are combined with the nylon fibers by hydrogen bonds or Van der Waals forces to provide a lighter color. As to the uniform dyeability, the acid dye is the first choice for dyeing nylon fibers, and thus the acid dye is a popular application used most in related industries.
With reference to FIG. 2 for a conventional polyamide fiber dyeing process, the polyamide fibers are modified in a modification process and dyed with the acid dye, wherein the conventional modification process of the polyamide adds a chain regulator of different types and additive quantities to increase the content of amino groups (—NH2) at the ends of a molecular chain of the nylon, while introducing a functional group with a special structure or adds a dye leveling agent or another co-agent in the dyeing process and performing a supersonic treatment, and finally a color fixation is performed after the dyeing process takes place in an oxidation-reduction system or water is used as a ring opening agent to perform an open ring polymerization of the amide group (—NHCO—) to reduce the polymerization induction period and improve the reaction speed, such that when a new equilibrium is reached, the number of polymer molecules is increased, and the content of amino groups (—NH2) will be increased accordingly, and the temperature before/after the hydrolysis and polymerization of the amide group (—NHCO—) will be increased appropriately, such that the content of amino groups (—NH2) at the ends of the molecular chain can be increased to achieve the modification effect.
Since the content of amino groups (—NH2) at the ends of the molecular chains of the nylon is very low (about 5˜10% of wool only), therefore the aforementioned modification process still cannot achieve the effect of improving the content of amino groups (—NH2) significantly. In other words, the dyeing effect of the nylon is relatively poor. Obviously, the conventional nylon fiber dyeing process has the following drawbacks:
1. The conventional process can achieve a mid-depth dyeing effect only. Since the acid dye and the polyamide are combined by the ionic bond or the electrostatic force, the bonding is relatively weak, and only a mid-depth dyeing effect can be obtained.
2. The conventional process generally results in poor dye fastness, light fastness, and washing fastness. The color of a dyed nylon processed by the conventional polyamide fiber dyeing process may be faded or stained easily by rinsing or exposures to sunlight or gas. The conventional dyed nylon has poor dye fastness, light fastness, and washing fastness.
3. The conventional process gives a non-level dyeing quality and incurs a high cost. In the conventional deep dyeing process of polyamide fibers, color difference, color deviations and stained spots may occur easily due to the dyeing condition and the selection of co-agents. In the meantime, the conventional deep dyeing process of the nylon fibers involves complicated dyeing process and color fixation and incurs a high cost.
4. The conventional process requires a high dyeing temperature. The temperature for the conventional polyamide fiber dyeing process must be over 100˜120° C., and thus the process causes high costs and power consumptions.
Obviously, the conventional polyamide fiber dyeing process requires further improvements.
In addition, polyolefin (such as polyethylene and polypropylene) has the features of a light weight, a plentiful resource, a simple manufacturing process, a small specific gravity, and a low water absorption and the functions of chemical resistance, electrostatic resistance, and pollution resistance, and thus polyolefin is used extensively in many areas due to its functions and low production cost.
The non-polar structure of polyolefin is generally considered as a major hidden problem that polyolefin cannot be dyed, since the polyolefin fibers have a very low hydrophilic property, and thus the affinity between a dye and a chemical co-agent is poor, and conventional dyeing and printing methods are unable to achieve an expected dyeing effect. At present, an organic or inorganic dye is generally used for dyeing the polyolefin fibers and such method of coloring the polyolefin fibers incurs a low cost and achieves a better fastness. However, this method is suitable for a mass production of products in a single series of colors only, and unable to meet the requirements of the consumer market, and its drawbacks include an incapability of printing patterns and a high inventory, etc. As a result, polyolefin is primarily used for manufacturing a large quantity of carpets or a small quantity of clothes that require less color only. Therefore, it is an important subject for manufacturers to apply a general dyeing technique to the polyolefin fibers, and for scholars to do researches to improve the dyeing effect of polyolefin fibers, and some scientists have used a chlorination of sodium hypochlorite and a photo-chemical bromination to modify the polypropylene fibers in order to perform the dyeing with a cationic dye, and the modified polypropylene fibers and dye produce covalent forces to achieve the effects of enhancing the bleaching fastness, washing fastness, seawater fastness and moisture regain, while reducing the strength and requiring a post-treatment to improve the light fastness. Some manufacturers have also attempted using a series of polyurethane compounds and a radiating beam to polymerize the polypropylene compounds to produce a copolymer suitable for the dyeing process with a cation dye, an acid dye or a dispersive dye, and some manufacturers have added a polar additive to polypropylene to produce fibers that are dyed with an acid dye, and some manufacturers even have attempted using hydrogenated oligocyclopentadiene or wool to weave polypropylene fibers. With the aforementioned methods, manufacturers attempted to increase the dyeability of polypropylene, but also lowered the photo-sensitivity and mechanical property of the polypropylene at the same time. Mostly important, the high cost of the modification makes polypropylene unfavorable to commercial applications. The dispersive dye and the hydrophobic fiber having a good compatibility among molecules in supercritical carbon dioxide are suitable for a dyeing process without requiring any co-agents. With the aforementioned perfect PET dyeing technology, the dispersion of the dispersive dye in the fibers and the solubility of the dispersive dye of a supercritical condition are studied. The dispersion and solubility of dyes can be determined by the properties of the dyes. In addition, the dispersive dye in supercritical CO2 can be used for dyeing polyolefin fibers, and the dye can be a dispersive azo dye having a benzene ring structure, and thus its color is darker than a general dispersive dye. In addition to the high cost and the incapability for commercialization, the use of azo dyes is not recommended due to the issue of environmental protection and even prohibited in some developed countries (such as European Union). In summation of the description above, the conventional polyolefin fiber dyeing process still has the following shortcomings:
1. The conventional dyeing process only provides a mid-depth dyeing effect. Since the conventional modified polyolefin is dyed with a dispersive dye and the attraction force between physical bonds (such as hydrogen bonds or Van der Waal forces) has a weaker bonding, only a mid-depth dyeing effect can be obtained.
2. The conventional dyeing process has poor dye fastness, light fastness, and washing fastness. The polyolefin fibers dyed by the conventional dyeing process may be faded or stained easily under sunlight or exposure to special gases due to the poor dye fastness, light fastness, washing fastness and rubbing fastness.
3. The conventional dyeing process has a non-level dyeing quality and incurs a high cost. A color difference, a color deviation and a stained spot may occur easily due to the dyeing conditions and the selection of co-agents. In the meantime, the conventional deep dyeing process of the nylon fibers involves complicated dyeing process and color fixation and incurs a high cost.
4. The conventional dyeing process requires a high dyeing temperature. The temperature for the conventional polyamide fiber dyeing process must be over 90˜120° C., and thus it causes high cost and power consumption.
5. The conventional dyeing process is incompliant with the requirements of environmental protection. Azo dyes and metal-containing dyes are not recommended due to the issue of environmental protection, and they are even prohibited in some developed countries (such as European Union).
Therefore, the conventional polyolefin fiber dyeing process still has the foregoing shortcomings and requires immediate attention and feasible solutions.